The production of juices from various fruits and vegetables has commonly involved first extracting an initial or raw juice including substantial amounts of solids such as rag, pulp from juice sacs, pectinous material, seeds, etc. Such initial juices have been obtained by various juice extracation machines. Typical examples of such juice extraction machines have been disclosed, for example, in U.S. Pat. Nos. 2,631,625 and 4,170,935. In the first noted patent, a machine was disclosed in which fruit or the like was cut in half and transferred into conveyor cups. Rotary reamers were then driven into engagement with the conveyor cups to extract initial juice from the fruit.
Similarly, the second noted patent disclosed a machine wherein fruit or the like was cut in half and conducted through gradually convergent paths to flatten the halves and express or extract pulpy juice therefrom. These machines have been effective in a preliminary step for obtaining initial or raw juice. However, it is commercially desirable to remove solid components from the juice to provide a so-called finished juice.
Typical commercial machines for converting initial juice to finished juice, or for removing fluid components from other types of slurries, have been characterized as either so-called screw-type or paddle-type finishers. Screw-type finishers have commonly been provided with spring or air-loaded pulp escape valve means at their discharge ends. As the fluid or juice passes through a stationary sceen, substantial solids tend to build up near the discharge outlet and it is sometimes necessary to apply air pressure against the valve means to assure removal of additional juice through the built-up solids. Such action has been found to be generally detrimental to juice quality.
In earlier paddle-type finishers, the slurry was introduced into a stationary screen of conical or cylindrical shape. Helical blades were rotated within the screen for conveying the slurry solids along the screen and for forcing components of the slurry through the screen. The clearance between the elongated blades and the screen had to be adjusted to achieve the desired separation of fluids through the screen. This required loosening and tightening of the blade mountings and relatively tedious adjustment of the elongated blades which resulted in lost operating time.
More recently, a paddle-type finisher was disclosed in U.S. Pat. No. 4,518,621 issued May 21, 1985 to Alexander under assignment to the assignee of the present invention. That patent disclosed a finishing machine wherein the slurry was introduced into one end of a cylindrical screen driven in rotation for exerting centrifugal force on the slurry to urge fluid to pass from the slurry through the screen. Paddle means were arranged for rotation with the screen but at a different speed so that the paddle means continuously moved or spread the slurry toward the outlet axial end of the screen.
The finishing machine disclosed in the preceding patent was found to be very effective in separating highly finished juice or fluid from an initial juice or slurry. The improved finishing machine of the present invention includes many features in common with that finishing machine. Accordingly, the above-noted patent is incorporated herein by reference as though set forth in its entirety to assure a more complete understanding of the present invention.
Even though the finishing machine of the above patent proved very effective, it has been found desirable to further improve both the processing rate for finishing operations employing such machines and also to assure relatively complete extraction of juice from other solids in the initial juice in order to make such operations both efficient and economical.
The factors of operating capacity and the degree of juice extraction are obviously related. For example, a relatively dry solids discharge could be obtained with a finishing machine of the type disclosed in the above patent, but only at the expense of a relatively low feed rate. Conversely, the finishing machine of the above patent could accept a higher feed rate but the solids discharge was found to be excessively wet with juice.
Accordingly, there has been found to remain a need for an improved finishing machine and method of operation for facilitating both efficient and economic finishing operations.